Magnesium
also Mg · Magnesium glycinate · Magnesium citrate · Magnesium oxide · Magnesium L-threonate
Magnesium is an essential mineral sold in many salt forms. Meta-analyses of randomised trials find modest drops in blood pressure, largest in people with hypertension or low magnesium [1]. They also find improved insulin resistance with longer use [2] and fewer migraine attacks [3]. Evidence for sleep and depression is weaker but positive [4][5]. Which salt matters less than marketing suggests [6].
A cheap, low-risk mineral with real if modest effects on blood pressure, migraine and insulin resistance; the case for any one "premium" form is thin.
- meta-analysis
- RCT
- trial
- observational
- preclinical / case
- review / patent / other
- retracted
- + Lowers blood pressure, most in hypertension or low magnesium
- + Fewer and milder migraine attacks
- + Improves insulin resistance with four months or more of use
- − Effects in people with normal levels are small
- − Sleep evidence is low quality
- − Very large intakes have been fatal
Overview
Magnesium is absorbed through both passive and active pathways in the gut. How much gets in depends on the dose, the food it is taken with, and the body's current magnesium status [6].
Blood pressure has the most consistent evidence. A 2016 meta-analysis of 34 double-blind trials found that a median 368 mg a day for three months lowered systolic pressure by 2.0 mmHg and diastolic by 1.8 mmHg [7]. A 2025 meta-analysis of 38 trials found larger falls in people with hypertension who were already on treatment, and in those with low magnesium. It found no significant effect in people with normal blood pressure [1].
Insulin resistance: magnesium improved HOMA-IR, and four months or more of use also improved fasting glucose [2]. Migraine: oral magnesium reduced the frequency and intensity of attacks across 10 prevention trials [3].
Sleep and mood evidence is thinner. In older adults with insomnia, three small trials found people fell asleep about 17 minutes faster, but the evidence was rated low to very low quality [4]. One of those trials also found longer sleep and better sleep efficiency [8]. In mild-to-moderate depression, an open-label crossover trial of magnesium chloride found a 6-point improvement on the PHQ-9 depression scale within six weeks [9]. A meta-analysis of seven trials also found lower depression scores [5].
Mechanism
Magnesium's blood pressure effect tracks a small rise in serum magnesium. In one meta-analysis, 300 mg a day or one month of use was enough to raise serum levels and lower pressure [7].
Magnesium L-threonate is marketed for the brain. In a randomised trial in older adults with cognitive impairment, a formula based on it (MMFS-01) improved overall cognitive ability compared with placebo [10]. A 2025 trial of Magtein found better overall cognition and reaction time and a smaller improvement in self-reported sleep impairment. Ring-measured sleep did not change [11].
Safety
risks and cautions, not medical adviceVery large intakes can be dangerous. A 75-year-old woman died of hypermagnesaemia after drinking milk mixed with magnesium chloride as a folk remedy [12].
In the trials cited here, magnesium was well tolerated, including the Magtein trial [11].
- People with kidney disease should get medical advice before supplementing
- In rats, organic salts were only slightly better absorbed than inorganic ones [13]
- Blood pressure trials are highly heterogeneous, and effects in people with normal pressure are not significant [1]
- Sleep trials in older adults are few, small and at moderate-to-high risk of bias [4]
- The depression trial was open-label [9]
- Claims that one salt is far better absorbed are not well supported in humans [6]
Interactions
documented pairs only, not exhaustiveOther minerals taken in high doses, phytate, oxalate and some fibres reduce magnesium absorption. Protein and some non-digestible carbohydrates increase it [6].
- MelatonincompatibleNo interaction documented; commonly combined for sleep
- L-TheaninecompatibleNo interaction documented
FAQ
- Which form of magnesium is best?
- The evidence says less than marketing does. In rats, organic salts were only slightly better absorbed [13], and in humans dose and magnesium status matter more than the salt [6].
- Does magnesium lower blood pressure?
- Modestly, by about 2 to 3 mmHg overall, and more in people with hypertension or low magnesium [1][7].
- Does magnesium help sleep?
- In older adults with insomnia it shortened time to fall asleep by about 17 minutes, but the trials were few and low quality [4].
References
entry last reviewed 2026-09-18- [1]Magnesium Supplementation and Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Argeros Z, Xu X, Bhandari B et al.Hypertension 2025meta-analysis · humanPMID 41000008◌ unreviewed
- [2]A systematic review and meta-analysis of randomized controlled trials on the effects of magnesium supplementation on insulin sensitivity and glucose control.Simental-Mendía LE, Sahebkar A, Rodríguez-Morán M et al.Pharmacol Res 2016meta-analysis · humanPMID 27329332◌ unreviewed
- [3]Effects of Intravenous and Oral Magnesium on Reducing Migraine: A Meta-analysis of Randomized Controlled Trials.Chiu HY, Yeh TH, Huang YC et al.Pain Physician 2016meta-analysis · humanPMID 26752497◌ unreviewed
- [4]Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis.Mah J, Pitre TBMC Complement Med Ther 2021meta-analysis · humanPMID 33865376◌ unreviewed
- [5]Magnesium supplementation beneficially affects depression in adults with depressive disorder: a systematic review and meta-analysis of randomized clinical trials.Moabedi M, Aliakbari M, Erfanian S et al.Front Psychiatry 2023meta-analysis · humanPMID 38213402◌ unreviewed
- [6]Intestinal Absorption and Factors Influencing Bioavailability of Magnesium-An Update.Schuchardt JP, Hahn ACurr Nutr Food Sci 2017reviewPMID 29123461◌ unreviewed
- [7]Effects of Magnesium Supplementation on Blood Pressure: A Meta-Analysis of Randomized Double-Blind Placebo-Controlled Trials.Zhang X, Li Y, Del Gobbo LC et al.Hypertension 2016meta-analysis · humanPMID 27402922◌ unreviewed
- [8]The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial.Abbasi B, Kimiagar M, Sadeghniiat K et al.J Res Med Sci 2012RCT · humanPMID 23853635◌ unreviewed
- [9]Role of magnesium supplementation in the treatment of depression: A randomized clinical trial.Tarleton EK, Littenberg B, MacLean CD et al.PLoS One 2017RCT · humanPMID 28654669◌ unreviewed
- [10]Efficacy and Safety of MMFS-01, a Synapse Density Enhancer, for Treating Cognitive Impairment in Older Adults: A Randomized, Double-Blind, Placebo-Controlled Trial.Liu G, Weinger JG, Lu ZL et al.J Alzheimers Dis 2016RCT · humanPMID 26519439◌ unreviewed
- [11]The effects of magnesium L-threonate (Magtein®) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial.Lopresti AL, Smith SJFront Nutr 2025RCT · humanPMID 41601871◌ unreviewed
- [12]A fatal case of hypermagnesemia caused by ingesting magnesium chloride as a folk remedy.Torikoshi-Hatano A, Namera A, Shiraishi H et al.J Forensic Sci 2013case report · humanPMID 24020515◌ unreviewed
- [13]Study of magnesium bioavailability from ten organic and inorganic Mg salts in Mg-depleted rats using a stable isotope approach.Coudray C, Rambeau M, Feillet-Coudray C et al.Magnes Res 2005preclinical · animalPMID 16548135◌ unreviewed